A group of liberal state attorneys general signed a pact earlier this year to keep secret their attempts to punish fossil fuel companies for climate change, according to a copy of the agreement obtained by a conservative-leaning group.

A wide-ranging “common interest agreement” between the 18 attorneys general, led by New York Attorney General Eric Schneiderman (D), seeks to limit public disclosure of their climate investigations, including probes into Exxon Mobil Corp. that multiple states are conducting.

The agreement said officials involved in the probes should “refuse to disclose any shared information unless required by law.”

The right-leaning Energy & Environment Legal Institute (E&E Legal) obtained the agreement through public-records litigation with the District of Columbia, which is a party to the pact.